| 摘要 |
1,168,833. Recovering yeast &c. BRITISH PETROLEUM CO. Ltd. Jan.13, 1967 [Feb. 9, 1966], No. 5640/66. Heading C6F. Contaminants consisting of, or comprising, at least one hydrocarbon and water are removed from a solid material (micro-organism) by extracting the contaminated solid material, in an extraction stage consisting of one or more extraction steps, with a mixture of an alcohol and a hydrocarbon with which it forms an azeotrope, these being employed in the mixture at a ratio by volume within the range 30: 70 to 70:30. The treated solid material from the first extraction stage may be further extracted with a mixture of the alcohol and azeotrope-forming hydrocarbon in a second extraction stage. The extract fractions from the first and second extraction stages, either separately or after blending, are fed to a distillation stage for the separate recovery of; (a) an azeotropic mixture of the alcohol and the azeotropeforming hydrocarbon, (b) an azeotropic mixture of the alcohol and water, and (c) a residue fraction. Substantially all the azeotropic mixture of the alcohol and water is blended with part of the azeotropic mixture of the alcohol and azeotrope-forming hydrocarbon to give a mixture of the alcohol and azeotrope-forming hydrocarbon containing these materials at a ratio by volume in the range 30:70 to 70:30 for recycling to the first extraction stage. The contaminated material preferably is diluted with water before the extraction to give a ratio of water to total alcohol and azeotrope-forming hydrocarbon mixture added in the range 1:4 to 1:10 by weight. Examples are directed to extracting the following micro-organism products, after partial refining by centrifuging, treatment with a specified surface active agent and washing with water until the hydrocarbon content was less than 7% based on the dry weight of the micro-organism; (1, 3 and 5) Candida tropicalis or Hansenula suavesleus after cultivation upon a heavy gas oil of petroleum origin; and (2 and 4) Candida utilis after cultivation upon mixed C 10 -C 20 hydrocarbons containing normal paraffins. The solvent mixture consisted for the first extraction stage of 50% by weight of n-hexane and of isopropanol, and for a second extraction stage of 80% by weight of n-hexane and 20% by weight of isopropanol. The products were almost entirely freed from lipids. |
